The invention relates generally to laser devices and more particularly to a laser device for heat treating metals or other work surfaces.
The benefits of using an integrated laser beam to heat treat metal surfaces are known in the art. The integrated laser beam averages the energy from the laser beam over a treated surface. The averaged energy distribution thereby avoids back tempering that softens and weakens the treated surface.
In addition, the present integrators break the beam into many parts and focus the beams on an area that is typically rectangular. Even though it is possible to obtain a uniform spot using the present integrators, spatial coherence is destroyed because the spot is rectangular. Therefore, present segmented integrators cannot generate a uniform ring of heat.
Present laser beam integrators for cylindrical or conical surfaces use axicons or torroidal parabolas to focus the laser beam into a ring that heat treats metal surfaces. To obtain uniform energy distribution using the present integrators, the laser beam must be very symmetric. However, the high power lasers used for heat treating generally produce unsymmetrical and unstable beams.
There are many different ways of delivering a laser beam to a treated surface. The Akeel U.S. Pat. No. 4,969,722 discloses a device for delivering a collimated laser beam. A focusing lens is rotatable about an axis that is offset from a focal axis of the lens. The rotation of the lens causes a laser beam to trace a curve on a workpiece.
The Jimbou et al U.S. Pat. No. 4,367,017 discloses a laser beam reflection system for applying a laser beam to an area to be treated. This invention includes a set of reflective mirrors mounted in a welding head housing. The welding head housing is adapted to rotate about an axis such that the laser beam focused by a focusing mirror can be applied in a circular welding zone.
The Geary U.S. Pat. No. 4,196,461 discloses a pattern generating entertainment device capable of producing a circular pattern of light. The circular light pattern is produced by a rotating mirror that is set off of perpendicular to its rotational axis.
The Ward et al U.S. Pat. No. 3,797,908 discloses an optical apparatus which provides a mechanism for reflecting an optical beam with a mirror onto a work surface using the mirror that is angularly movable about a rotational axis and about a direction perpendicular to the rotational axis. Thus, the angular movements of the mirror cause the beam to scan over the work surface.